Structural diversity of Zn(ii) based coordination polymers constructed from a flexible carboxylate linker and pyridyl co-linkers: fluorescence sensing of nitroaromaticsElectronic supplementary information (ESI) available. CCDC 1562230-1562234. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7nj02651j

The flexible carboxylate linker, H 3 L = 5-(2-carboxybenzyloxy)isophthalic acid, and a group of N-donor co-linkers such as 1,2-di(4-pyridyl)ethylene (dpe), 1,2-di(4-pyridyl)ethane (1,2-dpe), 1,2-di(pyridin-4-yl)diazene (dpd), and 1,3-di(4-pyridyl)propane (1,3-dpp), give rise to five new coordination polymers (CPs) with Zn( ii ) ions. These are {[Zn 2 (L)(μ-OH)(dpe)(H 2 O)]} n ( 1 ), {[Zn(L)(1,2-dpe) 1.5 ]·H 2 O} n ( 2 ), {[Zn(HL)(dpd) 1.5 ] 2 ·2(H 2 O)} n ( 3 ), {[Zn(HL)(1,3-dpp)]} n ( 4 ), and {[Zn 5 (L) 4 (H 2 O) 2 ]·8(H 2 O) (1,2-dpe)} n ( 5 ). CP 1 forms a densely packed 3D framework with a rare topological type, ose ; 7/3/o5 ; sqc59 . Both CP 2 and 3 form [2+2] metallacyclic units which form a 1D chain that links other chains by strong O-H N type H-bonding to result in a 3D supramolecular network. CP 4 forms a 2D sheet structure stacking over each other by C-H π and π π interactions, to give rise to a 3D H-bonded supramolecular structure with topological type, sql/Shubnikov . CP 5 has two types of SBUs with a 3D anionic network where channels are filled up with the cationic 1,2-dpe ligands and water molecules which shows rare topological type, 6,10T9 . The photoluminescence sensing of nitroaromatic compounds, especially 2,4,6-trinitrophenol (TNP), by 1-5 indicates that these CPs could be potential candidates for developing luminescent sensors for selective sensing of these species. Five new Zn( ii ) based coordination polymers have been synthesized that were used in the sensing of nitroaromatic compounds via luminescence quenching.